Angular distribution of preequilibrium neutron emissions from heavy-ion reactions

The angular distribution of preequilibrium nucleons emitted in low- and medium-energy heavy-ion reactions is determined from the kinematics of nucleon-nucleon scattering inside the nuclear matter. In calculating the scattering kernels the excitation of the nuclear matter has been taken into account through a finite-temperature Fermi distribution of the nucleons. Neutron angular distribution in ¹²C+¹⁶⁵Ho reaction at 300 MeV incident energy and ²⁰N+¹⁶⁵Ho reaction at 600 MeV is calculated from two-body scattering kinematics and compared with the experimental data. The present calculations reproduce the experimental data fairly well in both cases. It has been found that in heavy-ion reactions the initial distribution of nucleons plays a significant role in determining the angular distributions.